Method of and system for designing an N-tier software architecture for use in generating software components

ABSTRACT

A system and method for designing a software architecture for utilizing software components in building extensible N-tier software applications is described, the method comprising specifying a set of software component rules for creating software components; specifying a set of tier rules for creating tiers; and specifying a set of assembly rules further comprising association rules by which each tier may be associated with at least one software component and linkage rules by which each tier may be linked to at least one other tier. The tier rules may further comprise a set of association rules by which each tier created with the set of tier rules may be associated with at least one software component created using the software component rules; a set of tier framework rules to provide an architected context for software components within a tier; and a set of package rules to provide for logical grouping of interfaces within a framework defined by the tier framework rules to provide a set of specific behaviors for the tier.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This nonprovisional U.S. national application, filed under 35U.S.C. § 111 (a), claims, under 37 C.F.R. § 1.78(a)(3), the benefit ofthe filing date of provisional U.S. national application No. 60/173,914,attorney docket no. D5407-00109, filed on Dec. 29, 1999 under 35 U.S.C.§ 111(b), the entirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to software design of softwarearchitectures and, in particular, to the design of a software componentarchitecture for the development of extensible tier software componentapplications, including compiled, interpreted, and on-the-flyapplications.

[0004] 2. Description of the Related Art

[0005] A variety of techniques are used by a programmer or codedeveloper to design or generate software program code. In one approach,software applications are designed as “monolithic” structures in whichthe various functions, such as data storage and application logic, arecompletely entwined. For example, given a set of system specificationsand functions which are to be implemented by a given application orprogram, the code developer designs a monolithic, independentlyexecutable program which implements the desired functions. Theprogrammer may use, for example, a high-level programming language suchas C++ and a code development tool to generate the high-level language,which is then compiled by a compiler to provide an executable version ofthe program.

[0006] One problem with this approach is that the applications aredifficult to maintain, and separate functional portions of the programare difficult to reuse because all portions of the program are entwinedand application-specific.

[0007] Accordingly, in the software field there have developed varioussoftware architectures in which application functionality is broken downinto smaller units. These units may be assembled to provide the overallfunctionality for a desired application. For example, a group ofcomponents may be assembled and compiled to provide a stand-alone,executable program. Alternatively, the components may be invoked andused in real-time, when the component's functionality is needed.

[0008] Because of the resource expenditure necessary to develop theseunits, it is desirable to be able to reuse these units, so that theirfunctionality may be employed in subsequent applications without havingto “re-invent the wheel” each time this functionality is needed. Incurrent software architectures, such as two-tier and three-tierarchitectures, some portions, such as data repositories and userinterfaces, are relatively easy to reuse. However, other types ofcomponents, such as those implementing application logic, are stillclumped in large blocks, making reuse of these components or theirvarious functions difficult. There is a need, therefore, for improvedsoftware component architectures and related software componentdevelopment techniques that avoid the drawbacks of the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] These and other features, aspects, and advantages of the presentinvention will become more fully apparent from the followingdescription, appended claims, and accompanying drawings in which:

[0010]FIG. 1 is a diagrammatic representation of the present invention's“N-tier architecture” paradigm;

[0011]FIG. 2 is a pictographic representation of a software factory;

[0012]FIG. 3 is a diagrammatic representation of a framework;

[0013]FIG. 4 is a flowchart diagram of rules;

[0014]FIG. 5 is a flowchart representation of the present invention'slife cycle rules; and

[0015]FIG. 6 is a flowchart generally describing the present invention'smethod for designing a software architecture for use in generatingsoftware components.

DETAILED DESCRIPTION

[0016] Referring generally to FIG. 1, the present invention comprises amethodology that applies an engineering and manufacturing orientedapproach to software production based on a well-defined architecture. Asused herein, “manufacturing” implies a method analogous to a softwarefactory. Using the present invention methodology, software applicationdevelopment can proceed as if it was a software manufacturing processwith an assembly line capable of assembling all types of intellectualproperty quickly and at the lowest cost

[0017] The present invention uses an “N-tier architecture” paradigm. Inan N-tier architecture, all functionality is broken down at the systemlevel into logical chunks or tiers 30 that perform a well-definedbusiness function. In the present invention's N-tier architecture thereis no limit to the number of tiers 30.

[0018] The present invention' N-tier software design architecture isemployed to develop software components 20 (shown in FIG. 1 as 20 a, 20b, and 20 c). As those of ordinary skill in the programming arts willappreciate, “N-tier” in the prior art may be thought of as implying ahierarchy such as with protocol stacks. However, as used herein,“N-tier” describes an architecture that is characterized by a pluralityof “N” tiers 30, each of which has a specified type and a specifiedinterface. Although a hierarchy can be defined for the tiers, nohierarchy is implicit in the N-tier architecture of the presentinvention.

[0019] Each software component 20 to be developed is associated with atleast one tier 30, depending upon the nature of the functions to beperformed by that software component 20 and tier 30. The presentinvention specifies a method and a system for creating architectures toimplement a N-tier system wherein a software component designer candesign or select each software component 20 to perform specifiedfunctionality and ensure that each software component 20 has theinterfaces specified by the architecture for that tier 30.

[0020] Using the methodology of the present invention, there is no limitto the number of tiers 30 or software components 20 that can beimplemented or defined. Rules for the architecture are specified wherebytiers 30 are not necessarily part of a hierarchy as in two- orthree-tier systems, but are logically interconnected using standardizedinterfaces so that each tier 30 can interact with one or more othertiers 30 as needed, i.e., a software component 20 within a given tier 30can interact with software components 20 of one or more other tiers 30as necessary.

[0021] The following terms are understood to have the following meaningsto those of ordinary skill in the programming arts for the presentinvention: TERM DEFINITION Architecture A set of design principles andrules used to create a design. COM Component Object Modeling. ComponentAn object that encapsulates, or hides, the details of how itsfunctionality is implemented and has a well-defined interface reusableat a binary level. CORBA Common Object Request Broker Architecture DCOMDistributed Component Object Model DLL Dynamic Link Library eventhandlermessage handling object Framework An architected context for businessobjects that modify the business objects' attributes or add newbehavior. GUID Globally unique identifier, e.g. a number having apredetermined number of bits that uniquely identifies a softwarecomponent JAVA a programming language Model A heterogeneous collectionof components whose relation- ships are enforced via a predetermined setof rules; a collection or instantiation of software components where thecollection or instantiation may be organized into a hierarchy Object Aprogramming structure encapsulating both data and functionality that aredefined and allocated as a single unit and for which the only publicaccess is through the programming structure's interfaces. A COM objectmust support, at a minimum, the IUnknown interface, which maintains theobject's existence while it is being used and provides access to theobject's other interfaces. Package A logical grouping of interfaceswithin a framework that provide a specific behavior such as messaging orconnecting. Sink Connection sink for messaging. Source Connection sourcefor messaging Tier A logical grouping of components that perform awell-defined, predetermined function.

[0022] It is understood that these descriptive constructs are notlimitations of the present invention, the scope of which is as set forthin the claims, but are rather meant to help one of ordinary skill in thesoftware programming arts more readily understand the present invention.More information on these functions and naming conventions, and on COMobjects in general, can be found in the Microsoft Developer's Network(MSDN) Library (January 1999), published by Microsoft Press andincorporated herein by reference.

[0023] A given N-tier architecture may be designed using the principles,rules, and methods of the present invention to satisfy the needs andcharacteristics of a given industry. The particular N-tier architecturedesigned in accordance with the present invention is then used togenerate software components 20 for an application. As used herein,“application” is understood to include compiled, interpreted, andon-the-fly applications, such as, by way of example and not limitation,CORBA, just-in-time, JAVA, and the like, as these terms are understoodby those of ordinary skill in the software programming arts. A “wizard”or other code development tool may also be designed, based on aparticular N-tier architecture, which allows the code developer togenerate software components 20 within the specifications of theparticular N-tier architecture. For example, the wizard may permit thecode designer to generate a software component 20 by selecting the tier30 for the software component 20 and ensuring that the softwarecomponent 20 is in compliance with the interface standards designatedfor software components 20 of that particular tier 30.

[0024] Referring still to FIG. 1, in an N-tier architecture designedusing the present invention, the present invention defines a methodologyfor specifying rules and methods that enable applications to beconstructed. A typical application built using architectures createdwith the present invention have functionality broken down at the systemlevel into logical chunks or tiers 30 that perform a well-definedfunction, such as a business function, according to rules as set forthherein. In a currently preferred embodiment, each tier 30 logicallygroups together software components 20 that have a similar type ofbehavior.

[0025] As discussed herein below, framework 40 is an architected contextfor software components 20 in a tier 30; that is, framework 40 specifiesa basic design structure, including base software components 20, and aset of standard interfaces for any software component 20 categorized asbelonging to that tier 30. Framework 40 comprises one or more packages42 which provide a method for collecting software components 20 andrepresent interfaces. A package 42 is a collection of interfaces thatprovide a specific behavior, such as messaging or connecting. Frameworks40 may have more than one package 42.

[0026] Each tier 30 is thus a logical grouping of packages 42 comprisingdiscrete software components 20 which adhere to the rules of the presentinvention. In a currently preferred embodiment, all software components20 created for or used by an application are put into an inventory (orcatalog) 700 of components, so that each software component 20 may bereusable by other application efforts. Further, software components 20are thus available for use by any other software component 20 that canuse its interface, including off-the-shelf components. Off-the-shelfcomponents, e.g. purchased components, may be incorporated into theN-tier architecture of the present invention such as by adding apredetermined interface to that off-the-shelf component as required bythe N-tier architecture of the present invention.

[0027] The present invention encompasses rules and methods to allowsoftware components 20 developed in accordance with a specified N-tierarchitecture to be used in a variety of ways. For example, rules mayexist to allow a group of N-tier architecture software components 20 tobe assembled and compiled to provide a stand-alone, executable program.Alternatively, rules may exist to allow software components 20 to becombined into tiers 30 and invoked at run-time, to form new uniqueapplications on-the-fly.

[0028] The present invention further encompasses rules to allow newsoftware components 20 to be created or purchased and then added toinventory 700 for future reuse. Inventory 700 may then be reused forsubsequent applications. As more software components 20 are developed,inventory 700 grows, thus further reducing the time and resources neededto develop new applications.

[0029] The present invention also encompasses rules to allow a givenN-tier architecture to be extended, for example by adding a new tier 30to result in a new, N+1-tier architecture. Many software components 20developed for the predecessor N-tier architecture will be immediatelyreusable in the incremental, N+1-tier architecture, and others will bereusable with relatively minor modifications.

[0030] In one embodiment, the present invention provides rules to defineand create a particular N-tier architecture with a specified, initialnumber and type of tiers 30 and with a specified interface architecturefor each tier 30, where each initial tier 30 satisfies one of a majorportion of system functionality, such as business logic (processing),data, and the like.

[0031] An N-tier architecture defined and implemented using the presentinvention may be thus adapted for use in numerous industries andcontexts, for example ship-building arts or medical arts as well asgeological industry type business objects. Each tier 30 defined andimplemented using the present invention specifies the types ofinterfaces that software components 20 associated with that tier 30 musthave. These interfaces are thus standardized interfaces for that N-tierarchitecture that allow software components 20 of a type of tier 30 tobe accessed by other software components 20 in other tiers 30. Asoftware component designer using the present invention defines therules for building software components 20 with the knowledge or abilityto access other software components 20, based on the interface specifiedby tier 30 for these types of software components 20.

[0032] In an embodiment, an N-tier architecture defined and implementedusing the present invention may specify which other types of softwarecomponents 20 (i.e. which tiers) that a given tier 30 must be able toaccess. In an alternative embodiment, this is left up to the softwarecomponent designer.

[0033] Each tier 30 will tend to have a unique set of interfaces,depending on the nature of the types of software components 20 groupedunder that tier 30. More common interfaces may include a specific,common first interface to allow a software component's 20 dependenciesto be collected by that software component 20 and accessed by othercomponents and a specific, common second interface to allow a softwarecomponent 20 to be identified at run time by another component.

[0034] In an embodiment, the N-tier architecture of the presentinvention may utilize an asynchronous architecture paradigm permittingsoftware components 20 to engage in asynchronous communication viaasynchronous messaging.

[0035] In a currently preferred embodiment, software component 20interfaces are implemented using Microsoft's COM specification. See,e.g., Essential COM by Don Box, published by Addison Wesley Longman,Inc, 1998 with an ISBN number of 0-201-63446-5. Only a softwarecomponent's 20 external interfaces are seen by the outside world. Commoninteraction standards, such as ActiveX, may be used to facilitatecommunication between software components 20 and reduce the need forconnective software between software components 20. Services provided bysoftware components 20 may networked together to support one or moredesired processes. These services can be reused and shared by othersoftware components 20. However, it will be apparent to those ofordinary skill in the programming arts that software components 20 maybe constructed using numerous other environmental paradigms, by way ofexample and not limitation including those required by LINUX, SUN (R)SOLARIS (R), Unix, or the like, or any combination thereof.

[0036] As currently contemplated, some tiers 30 may exist that are nottrue tiers 30, i.e. they do not exist to provide additional behavior tosoftware components 20. These tiers 30, such as a Wizard, Testing, orTemplate tier 30 shown in FIG. 1 generally as tier 600, may be presentto provide additional functionality. By way of example and notlimitation, a Wizard tier 30 may exist to provide a set of interactivehelp utilities that assists developers in quickly creating standardpresent invention components. A Testing tier 30 may be present tocontain software components 20 that exercise software components 20 orpackages 42 from functional tiers 30, record test results in a log, andnotify developers of the test completion status. Software components 20in a Template tier 30 may provide C++ implementation of persistence,collections, and iterators for standard present invention softwarecomponents.

[0037] Referring now to FIG. 2, a pictographic representation of asoftware factory, software components 20, whether purchased or created,may be placed into inventory 700 for future use using library orcataloging processes, all of which are familiar to those of ordinaryskill in the software programming arts. Software component 20 interfacesare standardized, with software component 20 functionality limited tothe characteristics and behavior unique to the software components 20they represent. The paradigm for the present invention is a softwareapplication assembly line as if in a software application factory. Asshown at 11, application requirements are first determined. The existinginventory 700 is then reviewed 12 for software components 20 that fitthe new application requirements. System requirements that do not existas stock software components 20 are created or purchased 13 and possiblyadded to inventory 700. A new application may then be created 14 fromthe preexisting stock software components 20 and/or the new softwarecomponents 20. The application may be created by combining softwarecomponents 20 at run-time to form new unique applications on-the-fly,making software reuse a practical reality.

[0038] Referring now to FIG. 3, framework 40 is an architected contextfor software components 20 in a tier 30; that is, framework 40 specifiesa basic design structure, including base software components 20, of atier 30. In addition, framework 40 specifies a set of standardinterfaces for any software component 20 categorized as belonging tothat tier 30. Framework 40 functions as a template or design pattern fortier 30, ensuring that basic design for tier 30 is uniform acrossprojects.

[0039] In the present invention, frameworks 40 encompass major designdecisions for their corresponding tiers 30, including what dependenciesa framework 40 has to other frameworks 40, how properties and interfacesare grouped, what interfaces are used, and where software component 20behavior belongs. For example, in a Visual tier 30 framework 40, aModel-View-Controller (MVC) may be used to specify the division of laborfor visual software components 20. In the MVC, data are handled by themodel, reaction to input is handled by the controller, and the viewcomponent handles drawing activities. By dividing the functionality upthis way, different business models may use the same controller or manydifferent views of the same business model.

[0040] Referring now to FIG. 4, the present invention's methodologyallows creation of rules that allow tiers 30 in a software applicationsystem to be extensible and subject to change as long as the system isin production. Therefore, the system is not restricted to apre-determined number of tiers; rather tiers 30 may be added, modified,or removed as the architecture and its applications evolve.

[0041] A system designer specifies 200 a set of software component rules210, each software component rule 210 comprising a given programmaticinterface, for at least one set of software components 20. It isanticipated that several sets of software components rules 210 mayexist, but the currently preferred embodiment has a single set ofsoftware component rules 210. Software component rules 210 specified mayfurther comprise rules on extending software components 20, such asaddition, modification, and deletion rules.

[0042] Specifying 200 software component rules 210 also comprisesspecifying rules on specifying behavior exhibited by each softwarecomponent. These rules 210 for specifying software component 20 behaviorfurther comprise rules on how each software component 20 encapsulatesdetails of how functionality is implemented for that software component20 and rules on creating a well-defined interface reusable at a binarylevel for each software component 20 whereby each software component 20may be made available for use by any other software component 20 thatcan use the well-defined interface of the first software component 20.Software component rules 200 allow for use of off-the-shelf softwarecomponents 20 by other software components 20.

[0043] Specifying 200 software component rules also comprises specifyingrules 210 on passing data to a software component, receiving data from asoftware component, manipulating software component 20 properties, andlibrarying or cataloging software components 20.

[0044] Specifying 200 software component rules may also comprisespecifying rules for designating software component function points,where these rules for designating software component function pointsallow implementing software component interfaces required by aparticular tier 30 to which the software component 20 belongs.

[0045] Specifying 200 software component rules comprises specifyingrules for manipulating software component 20 properties such as rulesfor adding, changing, and removing properties from a software component.This may include specifying at least one modification software componentrule 200 whereby a software component 20 created using the set ofsoftware component rules 200 can be modified individually, or an entireset of software component 20 rules can be manipulated, added, or deletedat one time. Other manipulating rules may be specified. By way ofexample and not limitation, it is often desirable to have a templateiterator class to facilitate accessing associations. Such a templateiterator class can be based at any software component's 20 associationsand can be used to iterate through all software components 20 in theassociation or only through a specific software component type.

[0046] Librarying software components rules 210 are also specifiedincluding rules for adding, changing, and removing software components20 from a software component 20 inventory 700 as well as rules onsearching for and selectively retrieving software components 20 frominventory 700. This may include specifying a set of library rules toallow grouping a set of software components 20 created using thesoftware component rules 210 into an interrogatable inventory 700 ofsoftware components, thus allowing for selectively placing softwarecomponents 20 into and retrieving software components 20 from inventory700. Additionally, library rules allow for addition off-the-shelfsoftware components 20 to inventory 700.

[0047] Software components 20 may execute processes independently,reacting to received messages to start and continue their own processingand sending messages to other software components 20 to start andcontinue processing. Accordingly, the present invention incorporatessoftware component rules 210 to allow asynchronous behavior in its basicarchitecture. Asynchronous behavior means that each software component20 executes within its own thread and time frame, informing dependentsoftware components 20 of its status or providing them with informationwhen significant events occur. Because all present invention softwarecomponents 20 operate independently, any software component 20 can bequeried for its status.

[0048] De-coupled software components 20 in the present invention systemcommunicate through the present invention's messaging system, which isalso an asynchronous process. Messages communicate events, information,and status between software components 20. Each software component 20may thus be event-driven, reacting to messages and events that aregenerated by other software components 20 in the system. In turn, eachsoftware component 20 generates its own events and communicates themback to the other software components 20 in the system.

[0049] The result of this architecture is that software components 20operate independently, simplifying maintenance and increasing softwarecomponent 20 usage.

[0050] Tier rules 310 must also be specified 300, including rules 310 onhow tiers 30 are associatable with a set of software components 20created using the software component rules 210. Tier rules 310 compriseinterface rules to allow tiers 30 to interface programmatically;software component manipulation rules to allow addition, modification,and removal of software components 20 from a tier, and rules for testingsoftware components 20 to ensure that these software components 20comply with tier rules 310. Additionally, tier rules 310 allow forextending tiers 30 such as by specifying rules on allowing modificationof software component 20 attributes for software components 20associated with tier 30.

[0051] Tier rules 310 further comprise framework rules to specify how toallow the specification of dependencies a framework 40 has to otherframeworks 40; how properties and interfaces are grouped; whatinterfaces are used; and where software component 20 behavior belongswithin a tier 30.

[0052] Framework rules may further comprise rules on specifying at leastone package 42 for a framework 40 where the package 42 further comprisesa set of interfaces to provide a specific behavior.

[0053] Tier rules 310 are also specified for associating tiers 30 withsoftware components 20, linking and setting processing sequencing, andprocessing states.

[0054] Additionally, it is often desirable to redefine softwarecomponents 20 within tiers 30 or add or delete entire tiers 30 from anapplication. Accordingly, association rules provide for softwarecomponents 20 created using software component rules 210 to beassociated or disassociated from tiers 30. Tier rules 300 may furtherinclude behavior rules, interface rules, and rules defining dependencieson other tiers 30.

[0055] Assembly rules 410 are specified 400, comprising rules on methodsof assembly of tiers 30 and software components 20 into finalapplications, by way of example and not limitation including specifyinga basic design structure comprising base components for softwarecomponents 20 in tiers 30 and specifying a set of standard interfacesfor the software components 20 categorized as belonging to the tier 30.Additionally, assembly rules 410 may exist for defining componentdependencies, including connection rules for applications. Assemblyrules 410 may further comprise testing rules to ensure softwarecomponents 20 adhere to requirements such as to tier interfaces,framework interfaces, and package interfaces. Further, one or more rulesmay exist to defining component dependencies, including connectionrules, for on-the-fly applications as well as define how softwarecomponents 20 advertise behavior capabilities present in that softwarecomponent 20 including by way of example and not limitationcommunication interfaces.

[0056] Referring now to FIG. 5, a life cycle flowchart, the presentinvention's methodology allows application development to drive changesto the present invention's architecture using a set of life cycle rules.By way of example and not limitation, rules that define a desiredsoftware architecture are either designed as described above or selectedfrom a preexisting set of rules. Thus, a software architecture designedusing the present invention's method generates software components 20,tiers 30, and applications by using software component rules 210, tierrules 310, and assembly rules 410 for an initial design 50. The initialdesign may have a predetermined number of initial tiers 30.

[0057] The system implemented is put into production 52 and periodicallyreviewed for adjustments that may be necessary 54. If any tier 30 isdetermined to be in need of adjustment 56, it can be removed orotherwise modified 58. As additional requirements arise 60, new softwarecomponents 20 are created or existing software components 20 modified62, 64. Tiers 30 may be added, modified, or deleted 66 as applicationrequirements dictate.

[0058] Referring now to FIG. 6, once a list of required models andsoftware components 20 is determined 70, software components 20 arelogically grouped 72. A determination 74, 76 is then made to determineif any of the software components 20 already exist in inventory 700.Whenever possible, software components 20 are reused 78 from inventory700. Software components 20 that do not fit the current architecture maybe restructured to ensure conformance while retaining the originalintent of the requirement.

[0059] Additional software components 20 may be created 80 as neededafter review of specifications and current inventory 700. After new ormodified software components 20 successfully pass a testing andvalidation phase, new or modified software components 20 are assessedfor suitability 82 to become part of inventory 700. Software components20 that have potential for reuse are added 88 to inventory 700. Thesenew or modified software components 20 may thus be integrated into acurrent architecture, expanding the current architecture, i.e., adding86 one or more tiers 30 to accommodate them. By definition via the rigidimplementation of standard interfaces, a software component 20 from onetier 30 can be used by any software component 20 from any other tier,making tier 30 relationships of little importance. However, in practiceit is likely that certain software components 20 will primarily be usedby certain other software components 20.

[0060] In the operation of the preferred embodiment, referring back toFIG. 4, a system designer using the present invention method to create asoftware architecture specifies 50 a set of software component rules 210for creating software components 20.

[0061] The system designer also specifies 300 a set of tier rules 310for creating tiers 30.

[0062] The system designer also specifies 400 a set of assembly rules410. Linkage rules within assembly rules 410 allow for selected tiers 30to be standalone, such as Testing or Wizard tiers 30. The systemdesigner also specifies a set of interfaces for each tier 30, theinterfaces defining a set of functionality capable within the tier 30.In some cases, a set of tiers 30 will be specified, each tier 30 withina set having the same defined set of functionality capability.

[0063] Once a software architecture is architected, a user of thatsoftware architecture uses the architecture and rules to specify anextensible N-tier architecture comprising a plurality of tiers 30,wherein each tier 30 is associatable with at least one softwarecomponent 20. Software components 20, in turn, are specified accordingsoftware component rules 200 that comprise rules on properties andinterfaces for software components 20.

[0064] Referring now to FIG. 4 through FIG. 6, the method of presentinvention for system design for an N-tier architecture generallyenvisions implementing a set of principles, rules, and methods to effecta life cycle approach to creation of software-based applications usingan architecture created using the present invention's rules and methodsas discussed herein above. A set of rules are designed an implemented,by way of example and not limitation comprising rules 210 on creationand characteristics of software components 20; rules 310 on tiers 30 andmaintenance of software components 20 within an inventory 700, includingaddition, modification, location, extraction, and deletion of softwarecomponents within inventory 700; and rules 410 on building tiers 30 andapplications.

[0065] In some implementations, it may be desirable to have a base setof software components 20 which can be used, either as templates or asactual software components 20. Accordingly, in these instances, asoftware designer would specify and create a base set of architectedframeworks 40.

[0066] The present invention can be embodied in the form ofcomputer-implemented processes and apparatuses for practicing thoseprocesses. Various aspects of the present invention can also be embodiedin the form of computer program code embodied in tangible media, such asfloppy diskettes, CD-ROMs, hard drives, or any other computer-readablestorage medium, wherein, when the computer program code is loaded intoand executed by a computer, the computer becomes an apparatus forpracticing the invention. The present invention can also be embodied inthe form of computer program code, for example, whether stored in astorage medium, loaded into and/or executed by a computer, ortransmitted as a propagated computer data or other signal over sometransmission or propagation medium, such as over electrical wiring orcabling, through fiber optics, or via electromagnetic radiation, orotherwise embodied in a carrier wave, wherein, when the computer programcode is loaded into and executed by a computer, the computer becomes anapparatus for practicing the invention. When implemented on ageneral-purpose microprocessor, the computer program code segmentsconfigure the microprocessor to create specific logic circuits to carryout the desired process.

[0067] Therefore, a system for designing a software architecture for usein generating software components for building software applications cancomprise numerous means for specifying a set of software component rulesfor creating software components, tiers, and assembly rules, all ofwhich will be familiar to those of ordinary skill in the computer arts,including, by way of example and not limitation, keyboards, mice,drag-and-drop interfaces, text editors, graphical editors, OLEinterfaces, and the like or any combination thereof. These means mayfurther comprise manual processes, heuristic processes, automatedprocesses, and the like, or any combination thereof, such as expertsystem driven or implemented designs, neural networks, and the like.

[0068] It will be understood that various changes in the details,materials, and arrangements of the parts which have been described andillustrated above in order to explain the nature of this invention maybe made by those skilled in the art without departing from the principleand scope of the invention as recited in the following claims.

What is claimed is:
 1. A method for designing a software architecture for utilizing software components in building N-tier software applications, the method comprising: a. specifying a set of software component rules for creating software components; b. specifying a set of tier rules for creating an extensible set of tiers, the tier rules further comprising: i. a set of association rules by which at least one software component created using the software component rules may be associated with or disassociated from at least one tier created with the set of tier rules; ii. a set of tier framework rules to provide an architected context for software components associated with a tier; and iii. a set of package rules to provide for logical grouping of interfaces within a framework defined by the tier framework rules to provide a set of specific behaviors for the tier; and c. specifying a set of assembly rules, the assembly rules comprising association rules by which each tier may be associated with at least one other tier and linkage rules by which each tier may be linked to at least one other tier.
 2. The method of claim 1 wherein specifying a set of software component rules for creating software components further comprises: a. specifying rules for specifying interfaces for each software component; and b. specifying rules for specifying behavior exhibited by each software component.
 3. The method of claim 2 wherein specifying rules for specifying behavior further comprises: a. specifying rules on how each software component encapsulates details of how functionality is implemented for that software component; and b. specifying rules on creating a well-defined interface reusable at a binary level for each software component; c. whereby each software component may be made available for use by any other software component that can use the well-defined interface of the first software component.
 4. The method of claim 1 further comprising specifying library rules for selectively placing software components into and retrieving software components from an inventory of software components.
 5. The method of claim 1 wherein software component rules comprise rules for supporting off-the-shelf components within software components or tiers, including rules to allow addition of off-the-shelf software components into the inventory.
 6. The method of claim 1 further comprising specifying at least one software component modification rule whereby software components may be extended, the at least one software component modification rule comprising addition, modification, and deletion rules.
 7. The method of claim 1 wherein the software component rules further comprise rules for designating software component function points.
 8. The method of claim 7 wherein the rules for designating software component function points further comprise rules to allow implementing software component interfaces required by a particular tier to which the software component belongs.
 9. The method of claim 1 wherein specifying a set of tier rules for creating an extensible set of tiers further comprises: a. specifying rules on allowing modification of software component attributes for software components associated with the tier; b. specifying rules to allow specifying what dependencies a framework has to other frameworks; c. specifying rules on how properties and interfaces are grouped; d. specifying rules on what interfaces are used; and e. specifying rules that specify where software component behavior belongs.
 10. The method of claim 1 wherein the framework rules further comprise rules on specifying at least one package for a framework, the package further comprising a set of interfaces to provide a specific behavior.
 11. The method of claim 1 further comprising: a. specifying a basic design structure comprising base components for software components in the tier; and b. specifying a set of standard interfaces for the software components categorized as belonging to the tier.
 12. The method of claim 1 wherein specifying a set of assembly rules further comprises: a. specifying rules to allow assembling and compiling at least one tier to provide a stand-alone, executable program; and b. specifying rules on allowing combining software components and invoking an assembled application at run-time to form new unique applications on-the-fly.
 13. The method of claim 1, wherein the software component rules specify rules allowing each software component to execute asynchronously within its own thread and time frame and to inform dependent components of its status or provide dependent components with information when predetermined events occur.
 14. The method of claim 1 further comprising specifying rules to allow defining one or more techniques to allow a software component to traverse a model, the model comprising one or more software components.
 15. The method of claim 14 wherein the traversal of a model uses a predetermined interface.
 16. The method of claim 1 further comprising specifying rules on implementing a template iterator class to facilitate accessing associations.
 17. The method of claim 16 wherein the template iterator class can be based at any software component's associations and can be used to iterate through all software components in the association or only through a specific software component type.
 18. A method for generating software components for use in an N-tier software application, the software components having a predetermined structure, the method comprising: a. providing a software component architecture comprising a plurality of tiers, wherein each tier may be associated with at least one of the software components, each tier further comprising a predetermined set of interfaces for that tier, the interfaces defining a set of functionality capable within that tier; and b. for a selected one of the plurality of tiers, providing at least one of the software components to satisfy the functionality of the tier wherein the at least one of the software components provides a predetermined set of interfaces specified for the selected one of the plurality of tiers.
 19. The method of claim 18 wherein the software component is reusable by any system employing software components designed in accordance with the method of claim
 18. 20. The method of claim 18, further comprising: a. specifying a set of tier framework rules to provide an architected context for software components within a tier; and b. specifying a set of package rules to provide for logical grouping of interfaces within a framework defined by the tier framework rules to provide a set of specific behaviors for the tier.
 21. The method of claim 20, wherein the tier framework rules further comprise: a. specifying rules on specifying dependencies a framework has to other frameworks; b. specifying how properties and interfaces are grouped; c. specifying what interfaces are used; and d. specifying where software component behavior belongs.
 22. The method of claim 21, further comprising specifying rules on defining packages, the packages comprising grouping of interfaces within a framework into subsets of interfaces to specify how a specific behavior, such as messaging or connecting, is to be provided.
 23. A method of system design for an N-tier architecture, the architecture comprising software components and tiers, the method comprising: a. determining a set of application requirements; b. determining a list of required models and software components to satisfy the application requirements; c. logically grouping the software components into extensible tiers; d. determining if each software component in each tier is available in an inventory of components; e. using each software component found in the inventory if that software component is a required software component; f. restructuring software components in the inventory to ensure conformance while retaining the original intent of the requirement, if possible; g. adding additional software components if no existing software component in the inventory satisfies or can be restructured to satisfy a requirement; h. associating at least one software component with each required tier; and i. creating an application by defining and implementing linkages between the required tiers.
 24. The method of claim 23 further comprising: a. testing each new software component; b. testing each restructured software component; c. assessing each new software component for suitability to become part of the software inventory; d. assessing each restructured software component for suitability to become part of the software inventory; and e. adding the new or restructured components to the inventory if the new or restructured software component has potential for reuse are added to the software inventory.
 25. The method of claim 23 wherein the new or restructured software components are either tailored into the current architecture or the architecture is expanded by adding one or more tiers to accommodate the new or restructured software component.
 26. The method of claim 23 where software components that are so specific they can only be used in a current application are not added to the inventory.
 27. The method of claim 24 wherein testing comprises testing and validation.
 28. The method of claim 23 wherein adding additional software components if no existing software component in the inventory satisfies or can be restructured to satisfy a requirement further comprises: a. procuring an off-the-shelf software component from a third party; and b. providing the off-the-shelf software component with a predetermined interface to interface between the off-the-shelf software component and at least one tier.
 29. A system for designing a software architecture for use in generating software components for building software applications, the system comprising: a. at least one processing unit; b. at least one memory store operatively connected to the processing unit; c. N-tier design software executable within the at least one processing unit; d. software architecture specifications resident in the memory store for use by the N-tier design software, the software architecture specifications comprising specifications for a set of software component rules for creating software components, specifications of a set of tier rules for creating tiers, and specifications of a set of assembly rules; e. an input device, operatively in communication with the processing unit, for permitting input of the software architecture specifications; f. an output device, operatively in communication with the processing unit; and g. a communications pathway operatively connected to the processing unit.
 30. The system of claim 29 wherein the communications pathway is a network.
 31. The system of claim 30 wherein the network comprises asynchronous communications, synchronous communications, local communications, local area networks, wide area networks, and local bus networks.
 32. A system for designing a software architecture for use in generating software components for building software applications, the system comprising: a. means for specifying a set of software component rules for creating software components; b. means for specifying a set of tier rules for creating tiers, the tier rules further comprising: i. a set of association rules by which each tier created with the set of tier rules may be associated with at least one software component created using the software component rules; ii. a set of tier framework rules to provide an architected context for software components within a tier; and iii. a set of package rules to provide for logical grouping of interfaces within a framework defined by the tier framework rules to provide a set of specific behaviors for the tier; and c. means for specifying a set of assembly rules further comprising association rules by which each tier may be associated with at least one software component and linkage rules by which each tier may be linked to at least one other tier.
 33. A method for defining and implementing an N-tier software architecture for a system comprising at least one processing unit, at least one memory store operatively connected to the processing unit, N-tier designing software executable within the at least one processing unit, an input device operatively in communication with the processing unit for permitting input of the software architecture specifications, an output device operatively in communication with the processing unit, and a communications pathway operatively connected to the processing unit, the method comprising: a. loading the N-tier designing software into the memory store; b. executing the N-tier designing software; c. inputting a set of software component rules for creating software components into the memory store; d. inputting a set of tier rules for creating tiers into the memory store, the tier rules further comprising: i. a set of association rules by which each tier created with the set of tier rules may be associated with at least one software component created using the software component rules; ii. a set of tier framework rules to provide an architected context for software components within a tier; and iii. a set of package rules to provide for logical grouping of interfaces within a framework defined by the tier framework rules to provide a set of specific behaviors for the tier; e. inputting a set of assembly rules into the memory store, the assembly rules further comprising association rules by which each tier may be associated with at least one software component and linkage rules by which each tier may be linked to at least one other tier; and f. processing the software component rules, tier rules, and assembly rules using the N-tier designing software to create an N-tier software architecture.
 34. An N-tier software architecture stored in a storage media, the storage media comprising: a. a first plurality of binary values for creating software components using software component rules; b. a second plurality of binary values for creating tiers using tier rules; and c. a third plurality of binary values for assembling software applications from tiers and software components. 